Apparatus for obtaining gas samples



1964 J. D. BENNETT ETAL 3,

APPARATUS FOR OBTAINING GAS SAMPLES Filed April 18, 1960 INVqORB JOHN D. BENN v STANLEY B. MCCALEB ATTORNEYS United States Patent 3,151,689 APPARATUS FOR OBTAINING GAS SAlVIPLES John D. Bennett and Stanley B. McCaleb, Richardson, Tex, assiguors to Sun Oil Company, Philadelphia, P3 a corporation of New Jersey Filed Apr. 18, 1960, Ser. N0. 22,829 6 Claims. (Cl. 175-77) This invention relates to samplers for bore holes and has particular reference to apparatus for catching gas samples from bore hole cores.

In apparatus heretofore employed for extracting a core from the side wall or a bore hole, there has been no pro vision for effectively obtaining a sample of the gas originally in the core. In the use of these prior devices, as the core was raised to the surface of the bore hole all the gas within the core escaped as the pressure dropped and it was impossible to determine whether of not a particular core sample ever contained any gas or the composition of gas which it might have contained. Some of the constiutents of the extracted core may be gases in a liquid or vapor state by reason of the high pressures in the bore hole. As the core is raised toward the surface of the bore hole whereby there is a pressure reduction, these constituents change to the gaseous state and escape from the core. A knowledge of the constituents of the gas sample would be, of course, very helpful in analyzing the significance of the core sample.

The general object of this invention is the provision of apparatus for catching a sample of the gas contained in a bore hole core. In accordance with the invention, a gas catching chamber is positioned adjacent the core taker so as to receive gas escaping from the core as it is raised to the surface and as consequent reduction of pressure occurs. Means are provided within the gas chamber for closing the same after the gas has entered whereby a gas sample is captured within the chamber.

The general object and other objects and features of the invention will become apparent from the following description read in conjunction with the accompanying drawing, in which the single figure is an axial sectional view of a portion of a core taker comprising a gas sample catching apparatus in accordance with the present invention.

The core taking apparatus may comprise a drill stem section It which is connected in the drill string immediately above the drill collar or a section above the drill collar, and a plurality of core takers 12 mounted in pockets 14 in the drill stern section 1%. Core takers 12 and pockets 14 are longitudinally and circumferentially spaced in drill stem section 19 in any desired number. By way of example, the core taking apparatus may be of the type disclosed in the application of John D. Bennett and Preston E. Chaney, Serial No. 856,427, filed December 1, 1959; and comprises four tiers of core takers with each 'er comprising four circumferentially spaced core takers.

Although only one tier of core takers is shown in the drawing,,it will be apparent that each core taker 12 and each pocket 14 is similarily constructed. Each core taker 12 is in the form of a tube 16 open at one end and mounted in a fitting 18 which has a pin 2% extending therethrough to rotatably mount the tube 16 and fitting 13 on the drill stem section 16. The core taker 12 is thus mounted for movement from a downwardly extending position to an upwardly extending position. A torsion spring 22 is mounted on pin 20 and biases core taker 12 outwardly from the downwardly extending position thereof. A cylindrical sheath 24 is mounted on drill section for axial and rotatable movement and comprises an axially extending slot 26 for each tier of core takers 12. Slot 26 is movable into registration with the pockets 14 to permit outward movement of the core taker 12.

As is more fully described in said prior mentioned applictaion, the core takers 12 are movable from a downwardly extending position into engagement with the side walls 28 of the bore hole upon registration of the slot 25 with one of the pockets 14. When a core sample is taken, the drill stem islowered a short distance thereby driving the extended core taker 12 into the side wall 28 of the well. The core taker 12 swings outwardly and upwardly through a horizontal position and emerges from the side wall 28 when it is in a position extending outwardly and upwardly. As soon as the core taker is free of the side wall 23, the springs 22 flip the core taker 12 further upwardly and into the upper end portion of the pocket 14.

In accordance with the present invention, means are positioned within each of the pockets 14 to catch a sample of any gas which may escape from the core within the tube 16 after a core taking operation. Such means comprises an elongated capsule 3t removably mounted in the upper end of each pocket 14, as by clamps 32, and defining an internal chamber 34 communicating with a restricted passageway 36 at the lower end of the capsule 3%). Restricted passageway 36 is the only opening in the chamber Capsule 3i) defines a funnel 38 at the lower end thereof commuicadng with restricted passageway 36 and is positioned so that the funnel 38 is immediately above the open end of the tube 16 when the core taker 12 is in its upwardly extending position after a core sample has been taken. By this construction, the funnel 38 faces the only exposed portion of the core sample.

Chamber 34 contains an elongated float 41) which has an O-ring 42 mounted at the lower end thereof. Ring 42 is adapted to engage an annular valve seat 44 formed at the lower end of chamber 34 adjacent the restricted passageway 36. Float all is made of a plastic, such as, for example, the foam type, which is lighter than water and will only be slightly compressed when subjected to high pressures. Float 46 will thus retain its general shape even upon being subjected to the high pressures present in the bore hole but due to the pressure its volume will be reduced and will be positioned in accordance with the liquid level in chamber 34.

When the drill stem is lowered into the bore hole, the capsule chamber 34 is originally substantially filled with a liquid, such as water, and possibly a small amount of air. The float 40 is thus positioned at the upper end of the capsule. The liquid is retained within the chamber 34 before the capsule 3t enters the drilling mud by means of a diaphragm 35 closing the lower end of chamber 34. As the drill stem is lowered in the bore hole, the capsule 36 becomes immersed in the drilling mud and the ambient pressure increases. This increase in pressure will tend to deflect the diaphragm 35 upwardly by reason of the compression of the float 4t) and the dia phragm 35 will burst. However, when the diaphragm 35 bursts, the capsule 30 will be immersed in the drilling mud and the liquid therein will not drain out.

After the drill stem is lowered to the core taking position and the core taking operation is completed all the core takers 12 will be in the upwardly extending position with the exposed portion of the cores the tubes 16 facing the open bottom end of the capsule 30. However, with the drill stem within the bore at the core taking position, the high pressure on the core prevents the escape of any gas therefrom. After the core taking operation, sheath 24 is in a position to close all of the pockets 14 to thereby protect the cores from the turbulence of the drilling mud. As the drill stem is raised in the well, the pressure on the core is reduced whereby any gas therein (originally under the high pressure of the hydraulic head) ex-.

pands to a volume much greater than its original volume and escapes. Gas escaping from the core rises into the funnel 38 and through the restricted passageway 36 to displace the liquid in the chamber 34. As the escaping gas displaces the liquid in the chamber 34, the float 40 moves downwardly with the level of the liquid. When all the liquid is displaced by the gas, the ring 42 comes into engag'ement with the seat 44 to close the pssageway 36 by the valving action of ring 42 and float 40. Thus, a'sample of any gas within the core is captured within the capsule 30. When the apparatus reaches the surface, the capsule 30 may then be removed from the core taking apparatus with its associated core and analyzed.

It will be noted that as the capsule is raised toward the surface of the bore hole, the pressure decreases and more gas escapes from the core and passes into the capsule chamber 34. Since, this captured gas is undera considerable pressure, as the pressure on the exterior of thecapsule decreases, the captured gas expands to force any remaining liquid from the chamber 34 and to force the float 40 against the seat 44. This action will occur even if there was initially only a partial filling of the chamber 34. Thus, an excellent seal is provided at the seat 44 and the gas is captured and retained at a considerable pressure.

It is to be noted that the gas sampler in accordance with this invention would be operative without a diaphragm at the bottom of the capsule and without initially filling the capsule With a liquid before lowering into the bore hole. In this case, the float 40 rests on the seat 44'during the initial movement of the drill stem down the bore hole. However, when the capsule 30 enters the drillingmud, the float 40 is raised in accordance with the drilling mud which enters chamber 34 through passageway 36 to compress the air'originally within chamber 34. As the capsole is lowered further, thedrilling'mud will substantially fill the chamber 34 by reason of theextremelyhigh pressures'within the bore hole, thereby positioning the float 44 at the top of the capsule. When the core taking posi- 2. Apparatus for obtaining a sample of gas from a core extracted from a well comprising support means, a core taker mounted on said support means and movable through a core taking movement for extracting a core to a core extracted position, a container having a chamber therein and a passageway communicating with said chamber, said container being mounted on said support means with said passageway facing a portion of an extracted core, means guiding a portion of a gas escaping from the extracted core into said passageway whereby the escaping gas enters said chamber, and means closing said passage in response to the pressure of a gas within said chamber whereby a sample of the gas which has escaped -from the extracted core is captured within said container,

said container being adapted to contain liquid therein which may be supplied thereto through said passageway, and said closing means comprising a float member adapted to be supported by a liquid within said chamber, said float member being movable to close said passageway in response to the displacement of the liquid in said chamber by a gas.

tion-is reached, the capsule will thus be prepared to receive any gases escaping from the core in the same manner as discussed above. The capsule may now function in the above-described manner to capture a gas sample as the drill stem is raised to the surface. It will be noted that the gas as captured from the core is at a pressure many times greater than the atmospheric pressure originally on the air in the chamber whereby the captured gas will make up almost all of the final volume of gas retained in wardly extending position to an upwardly extending position for extracting av core, a container mounted on said support means above said tube, said container defining a chamber therein and a passageway communicating with the said chamber, said passageway facing a portion of the extracted core when said tube is in the upwardly extending position whereby a gas escaping from the core enters said chamber through said passageway, .and means closing said passageway in response to the pressure of ages within said chamber to capture a sample of any gas escaping from the core:

3. Apparatus for obtaining a sample of gas from a core extracted from a well comprising support means, a core taker mounted on said support means and movable I through a core taking movement for extracting a core to a core extracted position, a container having a chamber therein and 'a passageway communicating with said chamber, said container being mounted on said support means with said passageway facing a portion of an extracted core, means guiding aportion of a gas escaping from the extracted core into said passageway whereby the escaping gas enters said chamber, and means closing said passage in response to the pressure of a gaswithin said chamber whereby a sample of the gas which has escaped from the extracted core. is captured within said container, said container being adapted to contain liquid therein which may be supplied thereto through said passageway, and said passageway communicating with the lower end of said chamber, saidcontainer defining a valve seat within said chamber'around said passageway, said passageway closing means comprising a valve member including a float adapted to be supported out of engage: ment with said valve seat by a liquid within said chamber, said float being movable into engagement with said seat to close said passageway in response to the displacement of the liquid in said chamber by a gas.

4. Apparatus for taking a core sample from a well com-' prising support means, a side wall core taker mounted on said support means and movable through a core taking movement to a position containing an extracted core, a container mounted on said support means adjacent to and above said core taker when in the core extracted position,

said container defining a chamber therein, a passageway communicating with said chamber, said passageway facing a portion of the extracted core when said core taker is in said extracted position whereby a gas escaping from the 1 core enters said chamber through said'passageway, and

means closing said passageway in response to the pressure of a gas within said chamber to capture a'sample of any gas escaping from the extracted core. 7

5. Apparatus for obtaining *a sample of gas from a i core extracted .froma well comprising a side wall core taking apparatus including a core taker pivotable through a core extracting movement to a core extracted position, a container having a chamber therein and a passageway communicating with said chamber, said container being mounted on the core taking apparatus adjacent th'e core' taker with said'passageway facing .a portion of an extracted core, means guiding a portion of a gas escaping from the extracted core into said passageway whereby the escaping gas'enters said chamber, and means closing said passage in response to the pressure of a gas within said I chamber whereby asample of the gas which has escaped from the extracted core is captured within said container.

6. A gas sampler comprising support means, a side Wall core taker mounted on said support means for extracting a core from a drilling well bore at a core extracting position, said side Wall core taker being mounted for pivotal movement into the side wall of the Well bore for extracting a core to a core extracted position, and means positioned on said support means adjacent to and above said core taker when in the core extracted position for capturing gases released from the extracted core as the ambient pressure is reduced by movement of the sampler upwardly from the core extracting position toward the surface of the Well bore.

References (Iited in the file of this patent UNITED STATES PATENTS Halbert Aug. 10, 1937 Mounce Dec. 2, 1941 Spencer Aug. 10, 1943 McClinton June 13, 1950 Stokes June 26, 1951 True Jan. 27, 1953 Williams Apr. 7, 1959 Gardner et a1 No. 8, 1960 

6. A GAS SAMPLER COMPRISING SUPPORT MEANS, A SIDE WALL CORE TAKER MOUNTED ON SAID SUPPORT MEANS FOR EXTRACTING A CORE FROM A DRILLING WELL BORE AT A CORE EXTRACTING POSITION, SAID SIDE WALL CORE TAKER BEING MOUNTED FOR PIVOTAL MOVEMENT INTO THE SIDE WALL OF THE WALL BORE FOR EXTENDING A CORE TO A CORE EXTRACTED POSITION, AND MEANS POSITIONED ON SAID SUPPORT MEANS ADJACENT TO AND ABOVE SAID CORE TAKER WHEN IN THE CORE EXTRACTED POSITION FOR CAPTURING GASES RELEASED FROM THE EXTRACTED CORE AS THE AMBIENT PRESSURE IS REDUCED BY MOVEMENT OF THE SAMPLER UPWARDLY FROM THE CORE EXTRACTING POSITION TOWARD THE SURFACE OF THE WELL BORE. 